Controller for electric motors



May 19, 1931. 'c. STANSBURY ETAL 1,806,269

CQNTROLLER FOR ELECTRIC IOTORS Filed Dec. 20. 1928 2 Sheets-Sheet l ls/ V VEN TOR If LEW WWW A mm y y 19, 1931- c. STANSBURY ETAL 1,806,269

CONTROLLER FOR ELECTRIC IOTORS Filed Dec. 20, 1928 2 Sheets-Sheet 2 INVENTOR awn XW B Y 33W swarm M j A TTOR/VE) Patented May 19, 1931 UNITED STATES PATENT OFFICE CARRCLL STANSBURY, OF 'WAUWATOSA, AND NIELS L- MORTENSEN, OF MILWAUKEE, WISCONSIN, ASSIGNORS, BY MESNE ASSIGNMENTS, TO CUTLER-HAMMER, 1110., OF MILWAUKEE, WISCONSIN, A CORPORATION OF DELAWARE CONTROLLER non ELECTRIC MOTORS Application filed December 20, 1928. Serial No. 327347.

This invention relates to controllers for electric motors. i The invention is particularly applicable to controllers for motor driven machines such as planers, in which provision is made for effecting plugging and reversal of the driving motor upon operation thereof in op posite directions into given limits.

The invention has among its objects to provide an improved motor controller of the aforesaid character having improved means for controlling the strength of the shunt field winding of the motor during plugging operations. a I

Another object is to provide an improved controller of the aforesaid character in which provision is made for stopping the motor by dynamic braking under abnormal conditions in the supply circuit, or upon failure of the reversing switches to effect plugging of the motor within'a given interval in the cutting and return limits of the planer.

Another object is to provide a controller of the aforesaid character having improved means for insuring excitation of the shunt field winding of the motor in the proper direction for dynamic braking under no voltage conditions.

Another ob ec't is to'provide a controller of the aforesaid character having improved means for affecting inching operations of the'motor in opposite directions at a reduced speed. j 7

Various other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate an embodiment of the invention which will now be described, it being understood that the embodiment illustrated is susceptible of 40 modification without departing from the spirit and scope ofthe appended claims.

In the drawings Figure 1 illustrates the elements of the controller embodying the invention, and

Fig. 2 is an across-the-line diagram illustrating the circuit connections for the controller shown in Fig. 1. I

Referring to Fi 1, the same illustrates a driving motor M For operating a reciprocatingmachine toolisuch asa planer. Said. 1110* switch 7. Switches 1-2 and 3- 1 serve to selectively establish reverse power connections for the motor armature and it isassumed that the former set'of switches provides for operation of the motor in its cutting direction while the latter set provides for operation thereof in its return direction. Each of the accelerating switches 5 and 6 is provided with an operating winding a and a lockout winding 6, and as shown in Fig. 2

' the former switch is responsive to shunt the series field winding F and also a step of accelerating resistance R while the latter is responsive to shunt a step of accelerating resistance R The dynamic braking switch 7 is normally closed, and as shown in Fig. 2 the same provides for connection of a dynamic braking resistance R across the terminals of the motor armature.

The control means for the shunt field winding F of the motor includes electrore- I sponsive switches 9 and 10, adjustable speed regulating rheostats 11 and 12, and electroresponsive switches 18 and 14. Each of the switches 9 and 10.is provided with two sets of normally open contacts I) and 0, and two sets of normally closed contacts 0? and e.

The contacts 6 and c of switch 9 provide for connection of the shunt field winding F of the motor across the supply circuit in series with .rheostats 11 and 12, while the contacts ca'nd d thereof function to connect said field winding'across the motor armature through the medium of switch 10 for dynamic braking under no-voltage conditi0ns. Switch 10 provides for connection of the shunt field. winding across the motor armature in the proper relation for dynamic braking. Switches 13 and 14 are each provided with'a series operating winding a and a shunt holding winding b, and as hereinafter set forth the same are associated with the heostats 1,1

and 12 to exclude said rheostats from the shunt field circuit of the motor during starting and to thereafter provide for speed regulation o f the motor in its cutting direction by rheostat ll'andin its returndirection by rheostat 12.

The control means for the two sets of direction switches 12and ZL-l includes an,

, clectroresponsive relay 15, pendant switch aushbutton stations 16 and 17, amaster switch 18. Relay 15 1s provided with nor mally open contacts 6 and normally closed contacts 0, and as hereinafter set forth the energizing circuit thereof 'is' controlled throu'ghthe medium of a; normally open start push button 19,,and anormally closed stop push button 20 associated with station. 16. Relay 15' inits normal position establishes connections whereby the direction switches 1-2 and 3-4 can be selectively controlled by push-buttons 21 and 22 associated with each of the stations 16 and-17 to eii ect inching operation of the motor in either direction. Relay 15. in responding provides for automatic control of the direction switches 12,

. tacts 26 and 27 engage contacts 26 and 27 upon movement of the platen into its return limit.

The controller also includesa normally open no voltage relay 28 and a normally closed overload relay 29', the later having an operatingwinding a and a holding winding 6. Relay 28 controls the aforementioned switch 9-,'and, as hereinafter set forth said switch-in responding establishes a feed for certain of the aforementioned relays and switches through the medium of the overload relay 29. Also as shown in Fig. 1 certainoi the aforementioned switches and relays are provided with auxiliary contacts the purpose of which will be hereinafter more fully described in connection with the operation of the controller. I v

The operation of the 'aforedescribed controllerwill now be more fully described in connection with, Fig. 2.. The operating winding 28 of voltage relay 28 and the shunt holding winding 29 ofoverload relay 29 are permanently connected-in series across the supply circuit indicated byline I -L Relay 28 is thus normally energized and, connects the operating Winding 9? of switch 9 across the supply circuit Il -L The contacts 9 and 9? of switch 9 connect the shunt field winding F of the motor across the supply circuit L L in' series with the'rheostats 11 and 12, while the auxiliary contacts 9 of said switch establish a circuit from line L to a feed line L through the mediun of overload relay 29.1

Depression of the start pushbutton 19 the contacts 15 of said relay through contacts 27, 27, and 25 of master switch 18 and through the operating windings 1 and 2 oi direction switches 12 to line L Direction switches 12 in closing establish a circuit from line L through the series opperating winding 29 of the overload relay 29 through resistance R and series fields F and F through direction switch l to and through the motor armature A through the series operating coils 13 and 14 of switches 13 and 1st and resistance R and thence through the direction switch ,2 tovline L Energization of the series operating coils 13 and 14 of switches 13 and 14 effects of the motor and the motor thus starts with its shunt field winding fully excited. Push button 19 can then be released, and upon release thereofrelay 15and the dynamic brake switch 7 are maintained energized through the medium of the auxiliary contacts 7" of said latter switchand the stop push button closure of said relays to exclude the rheo- M stats 11 and 12 from the shunt-field circuit Immediately uponclosureof the direction switches 12the shunt; operating coil o of accelerating switch 5 is connected inparallel with the operating windings of said direct-ion switches by closure of the auxiliary contacts 2 of direction switch2. How-,

ever, accelerating switch 5 does not respond immed ately due'to the restraining action of its lockout w1nd1ng5? which is connected in shunt with resistance R Whenthe current in the motor circuit drops, to a given value the operating winding 5* overcomes the re straining action of the lockout winding 5? and accelerating switch 5' then closes to exclude resistance R and the field F from the armature circuit of themotor. Immediately upon closure of accelerating switch 5 the opcrating winding 6' of accelerating switch 6 is connected in parallel with the. operating windings of the direction switches 1- -2 through themedium of the auxiliary contacts 2 of the latter direction switch, auxiliary contacts 15 of relay 1 5 and theauxiliary contacts 5 of accelerating switch 5. Response of accelerating switch 6 is delayed due to the action of its lockoutwinding 6? which is connected across resistance R and "1 E of :switches 13 :and 14 from the armature circuit oflthe motor. Switch 13 then returns to normal position to include therheostat .1 in the shunt field circuit of '-tion to exclude rheostat 12 from 'the field circuit of the motor since the holding winding l a ithereof is energized bya circuit extending from line L ithrough the contacts of relay 15 through contacts 27, 27*,

and 2510f the master switch through the auxiliary contacts 2*. of direction switch 2,:auxilwary contacts 15 of switch 15 and thence through the'holding Winding 14 and a re-.

sistance V lJOill'I'lG L The shuntfield circuit is *thus weakened by inclusion of the cutting rheostat l1 and thespeed of the motor is de- -termined by the setting of said rheostat.

When the motor operates .into its cutting limit the master switch 18 is thrown into its adapted to remain inclosedvposition for a temporary per1od,.as hereinafter set :forth,

andthe direction switches 3-4: are'tnus energized by a'circuit extending from line L through contacts 15 of'switch 15 through contacts 27, 27", 26" and 26 of the master switch and thence through the operating windings of said direction switches to line L Upon closure of direction switches 3 and lthe motor armature and the operating windings '13 and 14 of switches and rl-i are connected across lines L H in the same manner as upon closure of switches 1 and 2,,except :that the'connections for the motor armature are reversed. The motor is thus plugged'nnd switches and-1d are energized to shunt the rheostats '11 and 12 after establishment of the plugging connections. lUpon closure of direction switch 3 thenuxiliary contacts 3 thereof connect the operating win ding of accelerating switch 5 in parallel with itheoperating windings of directionswitches 3 and but 01081116 of said accelerating switch is deiayed by its lockout winding 5". Lockout winding 5 isdesigned to permitclosure of accelerating switch 5 by its operating winding 5 as soon as the motor is brought to rest, and 'as herein-before set forth closure of said accelerating switch effects exclusion of resistance R and the series field winding F from the motor circuit. Upon closure of accelerating switch 5 the contacts 5 thereof connect the operating winding {3 of accelerating switch '6 [in parallel with-the operating windings 3 and 4* of the return direction switches through the medium of-contacts 3" of direction switch'3 and the auxiliary contacts 15 of relay 15. When the current in the motor circuit drops to a given valueafter reversal of the m'otoroperating winding'ti cit accelcrating switch 6 overcomes the restraining action of the lookout Winding 6 to effect closure of said accelerating switch. Closure of accelerating switch 6, as hereinbetore set forth, excludes resistance and the series operating windings 13 and ld -ofswitches land :14: from the motor circuit. Switch 1'4thendrops'outto include rh'eostat 12 in the shunt'field circuit oi the motor since the holding winding 14" of said switch is shunted'through auxiliary contacts 3 of direction switch 3 and 15 of -relay 1f However, switch 13 remains in closed :position to exclude rheostat 11 from the shunt field circuit, the holding winding :13 of said switch being-energized by a-circuitcxtending from line L through the contacts 15 of relay 15 through 'contacts 27, L27, 26 '.'and, 26 ofthe master switch, thiough auxiliary contacts 3 ofdirecti-on switch 3 and auxiliary con- Etacts .l5 -of relay 15 and thence :through {the holding winding 13 and a resistance w to line L Upon operation of the motor into its return limit the master "switch 18 is returned sto its icutting :po'sition and the controller againoperates in-a manner similar to that hereinbefore described to ;plug the motor .and then reverse the same.

In-connection with the foregoing it should be noted that each iti-me the master switch 518 is operated to reverse the motor both of the switches 13 and '14 are 'deenergized for inclusion'of both of the rheostats l1 and 12 in the shunt field circuit of the motor. Up-

on deenergization of both of the switches Band 14 the auxiliary contacts 13 and 14 thereof short-circuit the operating winding 7 0f the dynamic braking switch '7 through the medium of :the normally closed contacts of the start push button 19 and the sto push button 20. When-the'operating win ing 7 :18 short-circuited. the same acts by self-induction to delay return of the namic *braking switch 7 to closed position. Under normal conditions short-circuiting of the operating winding 7 is only momentary and the dynamic braking switch 7 remains in open position. However, if either set of direction switches ttails 'for any reason :to establish reverse power connections {qr the motor the switches 13 and 14 remain in normal position and the dynamic braking switch 7 thus returns to closed position after m5 a predetermined interval to connect resistance lt across the arma'ture'A tor'stopping of the motor by dynamic 'ibraking. Upon return oat switch 7 toclosed position the contacts 7 thereof deenergize relay 15 and said relay in opening interruptsthe feed circuit extending through itscontacts 15 for direction switches 12 and 3 -4, accelerating switches 5 and 6 and the switches 13 and 14. However, during dynamic braking switches 13 and 1d are maintained in closed position by their operating windings 13 and l l to thereby exclude rheostats 11 and 12 from the saunt field circuit of the motor. Dynamic braking switch 7 and relay 15 can be deenergized at any time to stop the motor by depression of the stop'push button .or by response of the overload relay 29.

' The push buttons 21 and 22 of stations 16 and 17 provide for control of the direction switches to effect inching operations of the motor. When the motor is stopped relay 15 is in normal position and the contacts 15 7 thereof establish a feed from line L to the,

push buttons 21 and 22. Each of the push buttons 21 is then adapted to complete the energizing circuit for the operating windings 1 and v2 of the out direction switches while each of the push buttons 22 is then adapted to complete the energizing circuit for the operating windings 3 and 4P of the return direction switches.

accelerating switch 5 is controlled as herelnbefore set forth to exclude resistance R and field F from the armature circuit.

However, accelerating switch 6 cannot respond during inching operations since the energizing circuit thereof is interrupted by the auxiliary contacts '15 of relay 15. Also it should be noted that during inching opof switch '9to normalposition the contacts 9 'and 9 thereof connect the field winding F in shunt with armature A, operating L windings 13 and 14 of switches 13 and 14 and resistance R through the medium of the switch 10. When switch 10 is deenergized the contacts 10 and 10 thereof establish connections which provide for excitation of the field winding F inthe proper direction for dynamic braking during operation of the motor in its return direction. However, when switch 10 is energized the contacts 10 and10thereof establish connections for excitation of the field F in theproper direction for dynamic braking during operation of the motor in its cutting direction;

Upon closure of either set of direction switches 12 or 3% Switch 10 is energized as I long as the motor is operating in its cutting direction by means which will now be described. As

hereinbeforeset forth, when the motor is Y operating in its return direction and reaches its return limit the direction switches 12 are closed to plug the motor, and when the motor is brought to restaccelerating switch 5 is closed. It is apparent from Fig. 2 that upon closure of the direction switches 1-2 and accelerating switch 5 the auxiliary contacts 1 associated with the former direction 10 the auxiliary contacts 10 thereof shunt the contacts 1 and 5-and as is apparentif no voltage conditions occur while the motor is operating in its cutting directionthe auxiliary contacts l0 maintain switch 10 energized to provide the required braking connections for the field F until the motor is brought to rest.

In connection with. the foregoing it should be noted that the requiredcontrol effects are obtained by a relatively small number of control switches, and it should also be noted that automatic operation of the motor, inch ing operations'and the transfer from automatic to inching operationis effected through the medium of the pendant switch provided with only fourpush buttons.

What we claim as new and desire to secure by Letters Patent is: c v i 1; The combination with a reversible driving motor, of means for selectively controlling reverse power connections for said motor for operation thereof in opposite directions between given limits'and for plugging thereof at said limits, and means for establishing a dynamic braking circuit for said motor upon. failure of said former means to establish. plugging connections for said'motor withina given intervalat said 7 limits.

2. The combination with a reversible drivmg motor, of means for selectively controlling reverse power connections for said motor to effect operation thereof in opposite directions between given limits and to effect plugging thereof at such limits, means for strengthening the field of said motor after establishment of plugging connections by said former means, and means under the 7 control of said last mentioned means for establishing dynamic braking connections for said motor upon failure of said first mentioned means to establish plugging-connections within a predetermined interval at either of said limits.

3. The combination with a reversible driving motor, of means for selectively controlling reverse power connections for sa d motor for operation thereof in opposite d1- rections between given limits and for plugging thereof at said limits, means for establishing dynamic braking connections for said motor upon failure of said former means to establish plugging connections within a given interval at said limits, and means associated with said latter means for rendering said former means ineffective to restart said motor after establishment of braking connections.

4. The combination with a reversible driving motor, of means for selectively controlling reverse power connections for said motor to effect operation thereof in opposite directions between given limits and to effect plugging thereof at said limits, an electromagnetic switch for controlling a dynamic braking circuit for said motor, said switch beng responsive upon establishment of power connections by said means, and means for deenergizing said switch upon failure of said first mentioned means to plug said motor within a predetermined interval at said limits.

5. The combination with a reversible driving motor, of means for selectively establishing reverse power connections for said motor, separate resistance devices each for determining the speed of said motor during operation thereof in one direction, a switch associated with each of said devices for shunting the same, each of said switches having an operating winding and a holding winding, the former winding being connected in a series in the armature circuit of said motor to effect response of said switches upon establishment of power connections for said motor, means for rendering both of said operating windings ineffective under given current conditions in the motor circuit and the shunt field circuit of said motor each fordetermining the speed of said motor in one direction, and means for rendering both of said devices ineffective during starting of said motor in either direction and for thereafter rendering said devices effective in accordance with the direction of operation of said motor, said last mentioned means being also adapted to render both of said devices ineffective following establishment of plugging connections for said motor.

7 The combination with a reversible driving motor, of means for selectively establishing reverse power connections for said motor for operation thereof in opposite directions between given limits and for plugging thereof at such limits, an electromagnetic switch for controlling a dynamic braking circuit for said motor, said switch being responsive to interrupt said circuit upon establishment of power connections for said motor, means for weakening the field of said motor upon establishment of power connections for said motor and for strengthening said field under given current conditions in the motor circuit, and means associated with said field control means for deenergizing said braking switch upon failure of said first mentioned means to effect plugging of said motor within a predetermined interval at said limits.

8. The combination with a reversible driving motor having a shunt field winding, of means for establishing dynamic braking connections for said motor under no voltage conditions in the motor circuit, said means including a pair of control switches, one of which is adapted under no voltage conditions to connect said shunt field winding in shunt with the armature of said motor through the medium of the other of said switches, and the other of said switches being normally adapted to connect said shunt field winding in a given relation with respect to the armature of said motor upon operation of said motor in one direction and in a reversed relation with respect thereto upon operation of said motor in an opposite direction.

9. The combination with a reversible driving motor having a shunt field winding, of means for establishing dynamic braking connections for said motor under no voltage conditions in the motor circuit, said means including a pair of electroresponsive control switches, one of said switches being adapted under no voltage conditions to connect said shunt field winding across the motor armature through the medium of the other of said switches, andsaid latter switch being normally adapted to connect said shunt field winding in a given relation with respect to the motor armature upon operation of said motor in one direction and means responsive upon operation of said motor in a reverse direction to effect response of said latter switch for connection of said shunt field Winding across the motor armature in a reversed relation with respect thereto.

In witness whereof, we have hereunto subscribed our names.

NIELS L.- MORTENSEN. CARROLL STANSBURY.

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